Transcript Electrolyte Replacement

Electrolyte Replacement
Professor Magdy Amin RIAD
Professor of Otolaryngology.
Ain shames University
Senior Lecturer in Otolaryngology
University of Dundee
PRINCIPLES OF FLUIDS AND
ELECTROLYTES
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Fluid Compartments Example: 70-kg male
Total Body Water: 42,000 mol (60% of BW)
Intracellular: 28,000 mL (40% of BW)
Extracellular: 14,000 mL (20% of BW)
Plasma: 3500 mL (5% of BW)
Interstitial: 10,500 mL (15% of BW)
Water Balance
70-kg male
• The minimum obligate water
requirement
to maintain homeostasis (assuming normal
temperature and renal concentrating ability
and minimal solute [urea, salt] excretion) is
about 800 mL/d, which would yield 500
mL of urine.
Normal Intake
• Oral liquids: 1500 mL
• Oral solids: 700 mL
• Metabolic (endogenous): 300 mL
“Normal” Output:1400-2300 mL/d
• Urine: 800-1500 mL
• Stool: 250 mL
• Insensible loss: 600-900 mL (lungs and skin).
(With fever, each degree above98.6 F adds 2.5
mL/kg/d to insensible loss; insensible losses are
decreased if a patientis on a ventilator; free water
gain may occur from humidified ventilation.)
Baseline Fluid Requirement
• Afebrile 70-kg Adult: 35 mL/kg/24 h
• If not a 70-kg Adult: Calculate the water
requirement according to Kg Method:
• For the first 10 kg of body weight: 100 mL/kg/d
plus
• For the second 10 kg of body weight: 50 mL/kg/d
plus
• For the weight above 20 kg: 20 mL/kg/d
Electrolyte Requirements:
70-kg adult
• Sodium (as NaCl): 80-120 mEq (mmol)/d
(Pediatric patients, 3-4 mEq/kg/ 24 h
[mmol/kg/24 h])
• Chloride: 80-120 mEq (mmol)/d, as NaCl
• Potassium: 50-100 mEq/d (mmol/d) (Pediatric
patients, 2-3 mEq/kg/24 h [mmol/kg/24 h]).
• Calcium: 1-3 gm/d,
• Magnesium: 20 mEq/d (mmol/d).
Electrolyte Requirements
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Potassium:
In the absence of hypokalemia and with normal renal function, most of this is excreted
in
the urine. Of the total amount of potassium, 98% is intracellular, and 2% is extracellular.
Thus, assuming the serum potassium level is normal, about 4.5 mEq/L (mmol/L), the
total
extracellular pool of K+ = 4.5 ?14 L = 63 mEq (mmol). Potassium is easily interchanged
between intracellular and extracellular stores under conditions such as acidosis.
Potassium
demands increase with diuresis and building of new body tissues (anabolic states).
Calcium: 1? gm/d, most of which is secreted by the GI tract. Routine administration is
not needed in the absence of specific indications.
Magnesium: 20 mEq/d (mmol/d). Routine administration is not needed in the absence
of specific indications, such as parenteral hyperalimentation, massive diuresis, ethanol
abuse (frequently needed) or preeclampsia.
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Glucose Requirements
• 100-200 g/d (65-75 g/d/m2).
During starvation, caloric needs are supplied by body fat and protein;
the majority of protein comes from the skeletal muscles.
Every gram of nitrogen in the urine represents 6.25 g of protein broken
down.
The protein-sparing effect is one of the goals of basic IV therapy.
The administration of at least 100 g of glucose/d reduces protein loss by
more than one-half.
Virtually all IV fluid solutions supply glucose as dextrose (pure
dextrorotatory glucose).
Pediatric patients require about 100-200 mg/kg/h.
COMPOSITION OF
PARENTERAL FLUIDS
• Parenteral fluids are generally classified
based on molecular weight and oncotic
pressure.
• Colloids have a molecular weight of >8000
and have high oncotic pressure.
• Crystalloids have a molecular weight of
<8000 and have low oncotic pressure.
Potassium
• Potassium balance depends on the
interaction of internal and external
homeostatic mechanisms.
• Only when one or both systems are
disturbed acutely or impaired chronically
does plasma K+ change markedly
Internal Balance
1. Acid-Base
2. Insulin
3. Mineralcorticoids
4. Catecholamines
1. Acid-Base
• With increasing extracellular H+ concentration (acidosis),
K+ moves from the intracellular to the extracellular
compartment in exchange for H+.
• The increase in plasma K+ concentration is small at first,
but increases for a time, as the acidosis continues.
• However, K+ is lost in the urine, and one sees a lessening
of the effect of acidosis on serum K+.
• The K+ changes seen with metabolic alkalosis are not well
understood and are complicated by the kaliuresis that
occurs. Some intracellular shift of K+ does occur, but the
decrease in serum K+ is mainly due to renal loss.
Internal Balance
2. Insulin
• Insulin stimulates K+ uptake by muscle and
hepatic cells.
3. Mineralcorticoids
• Aldosterone makes cells more receptive to
the uptake of K+ and increases renal
excretion of K+.
4. Catecholamines
• Epinephrine initially increases plasma K+ because
of combined alpha and beta receptor stimulation,
which releases K+ from the liver.
• The response is followed by a decrease in plasma
K+ caused by beta-receptor stimulation, which
enhances K+ uptake by muscle and liver.
• The end result is a decrease in serum K+
• Propranolol impairs cellular uptake of K+.
External Balance
Renal Potassium Excretion
• 1. Potassium Intake - An acute or chronic increase
in K+ intake leads to increased secretion in the
distal convoluted tubule.
• 2. Sodium Intake and Distal Tubular Flow Rate A sodium load will increase flow past the distal
tubule and cause K+ wasting. The converse is true
too.
• 3. Mineralcorticoids - A mineralcorticoid
deficiency leads to K+ retention and Na+ wasting,
just as excess leads to opposite changes.
External Balance
• GI Potassium Excretion
• Fecal excretion of K+ normally is small, but
with diarrhea disorders, K+ loss increases
significantly.
Hypokalemia
K+ <3.6 mEq/L (mmol/L)
Mechanisms: Due to inadequate intake, loss, or intracellular shifts
Inadequate Intake. Oral or IV
GI Tract Loss.
• vomiting, diarrhea, excess sweating, villous adenoma, fistula
Renal Loss. Diuretics and other medications (amphotericin, high-dose penicillins,
• aminoglycosides, cisplatin), diuresis other than diuretics (osmotic, eg, hyperglycemia or
ethanol-induced), vomiting (from metabolic alkalosis from volume depletion), renal
tubular disease (renal tubular acidosis type II [distal], and [proximal]), Bartter syndrome
(due to increased renin and aldosterone levels), hypomagnesemia,natural licorice
ingestion, mineralocorticoid excess (primary and secondary hyperaldosteronism,
Cushing syndrome, steroid use), and ureterosigmoidostomy
Redistribution (Intracellular Shifts). Metabolic alkalosis (each 0.1 increase in pH
• lowers serum K+ approximately 0.5-1.0 mEq/L, due to intracellular shift of K+), insulin
administration, beta-adrenergic agents, familial periodic paralysis, treatment of
megaloblastic anemia
Symptoms
• Muscle weakness, cramps, tetany
• Polyuria, polydipsia
Signs
• Decreased motor strength, orthostatic
hypotension, ileus
• ECG changes
Treatment:
• The therapy depends on the cause.
• A history of hypertension, GI symptoms, or use of
certain medications may suggest the diagnosis.
• A 24-h urine for potassium may be helpful if the
diagnosis is unclear.
• Levels <20 mEq/d suggest
extrarenal/redistribution,
• >20 mEq/d suggest renal losses.
Treatment:
A serum potassium level of 2 mEq/L (mmol/L) probably
represents a deficit of at least 200 mEq (mmol) in a 70-kg
adult;
• to change potassium from 3 mEq/L (mmol/L) to 4 mEq/L
(mmol/L) takes about 100 mEq (mmol) of potassium in a
70-kg adult.
Treat underlying cause.
• Hypokalemia potentiates the cardiac toxicity of digitalis. In
the setting of digoxin use, hypokalemia should be
aggressively treated.
• Treat hypomagnesemia if present. It will be difficult to
correct hypokalemia in the presence of hypomagnesemia.
Rapid Correction.
• Give KCl IV.
• Monitor heart with replacement >20 mEq/h.
• IV potassium can be painful and damaging to
veins.
• Patient <40 kg: 0.25 mEq/kg/h x2 h
• Patient >40 kg: 10?0 mEq/h x2 h
• Severe [<2 mEq/L (mmol/L)]: Maximum 40
mEq/h IV in adults
• In all cases check a stat potassium following each
2-4 h of replacement.
Slow Correction.
• Give KCl orally
• Adult: 20-40 mEq two to three times a day
(bid or tid)
• Pediatric patients: 1-2 mEq/kg/d in divided
doses
Potassium disorders
Treatment of Hypokalemia
• The treatment of hypokalemia includes repletion
of K+ and removal of the cause of hypokalemia.
• Emergency situation, in the presence of
arrhythmias, K+ can be replaced intravenously by
a solution containing 40 to 60 meq/l, infused at a
rate of no more than 40 meq/hour.
• Any magnesium deficiency must be corrected in
order to correct the hypokalemia.
Hyperkalemia
• Potassium is released from cells at times of stress,
injury, acidosis; but the kidney is able to regulate
potassium well, and hyperkalemia is rarely a
problem.
• However, in the presence of renal failure
hyperkalemia becomes a common problem.
• It is generally treated if there is an abrupt rise from
normal to >6.5 meq/liter or if any level is associated
with EKG changes.
Hyperkalemia
(K+ >5.2 mEq/L (mmol/L)
Mechanisms: Most often due to iatrogenic or inadequate renal excretion of potassium.
• Pseudo-Hyperkalemia. Due to leukocytosis, thrombocytosis, hemolysis, poor
venipuncture technique (prolonged tourniquet time)
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Inadequate Excretion. Renal failure, volume depletion, medications that block
potassium excretion (spironolactone, triamterene, others), hypoaldosteronism (including
adrenal disorders and hyporeninemic states [such as Type IV renal tubular acidosis],
NSAIDs, ACE inhibitors), long-standing use of heparin, digitalis toxicity, sickle cell
disease, renal transplant
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Redistribution. Tissue damage, acidosis (a 0.1 decrease in pH increases serum K+
approximately 0.5-1.0 mEq/L due to extracellular shift of K+), beta-blockers, decreased
insulin, succinylcholine
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Excess Administration. Potassium-containing salt substitutes, oral replacement,
potassium in IV fluids
• Symptoms: Weakness, flaccid paralysis, confusion.
• Signs:
• Hyperactive deep tendon reflexes, decreased motor
strength
• ECG changes, such as, peaked T waves, wide QRS, loss
of P wave, sine wave,
• asystole
• K+ = 7-8 mEq/L (mmol/L) yields ventricular fibrillation
in 5% of cases
• K+ = 10 mEq/L (mmol/L) yields ventricular fibrillation
in 90% of cases
Treatment
• Monitor patient on ECG if symptomatic or if K+
>6.5 mEq/L; discontinue all potassium intake,
including IV fluids; order a repeat stat potassium
to confirm.
• Pseudo-hyperkalemia should be ruled out. If doubt
exists, obtain a plasma potassium in a heparinized
tube; the plasma potassium will be normal if
pseudo-hyperkalemia
is present.
Rapid Correction.
• These steps only protect the heart from potassium
shifts, and total body potassium must be reduced
by one of the treatments shown under Slow
Correction.
• Calcium chloride, 500 mg, slow IV push (only
protects heart from effect of hyperkalemia)
• Alkalinize with 50 mEq (1 ampule) sodium
bicarbonate (causes intracellular potassium shift)
• 50 mL D50, IV push, with 10-15 units regular
insulin, IV push (causes intracellular potassium
shift)
Slow Correction
• Sodium polystyrene sulfonate (Kayexalate)
20-60 g given orally with 100-200 mL of
sorbitol
• or 40 g Kayexalate with 40 g sorbitol in 100
mL water given as an enema.
• Repeat doses qid as needed.
• Dialysis (hemodialysis or peritoneal)
Correct Underlying Cause.
• Such as stopping potassium-sparing
diuretics, ACE inhibitors, mineralocorticoid
replacement for hypokalemia
Treatment
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Restrict Exogenous K+
Calcium gluconate - 10 to 30 ml of 10% solution over 3 to 5 minutes
NaHCO3 - 50 to 100 ml of 7.5% solution
Hyperventilation will also create an alkalosis and drive K+ into cells
Avoid hypoventilation,
Glucose - insulin - 500 ml of 10% dextrose plus 10 units regular
insulin or 50 - 100 gm with 10 -20 units regular insulin
Lasix, ethacrynic acid, or bumex
Oral or rectal sodium or calcium polystyrene with sorbitol
Peritoneal dialysis or hemodialysis
Transvenous pacemaker
Sodium Physiology
1. Sodium and its anions make up about 90% of the
total extracellular osmotically active solute.
2. Serum osmolality (mOsm/kg H20) = 2 X [Na+] +
[glucose]/18 + [BUN]/2.8
3. For practical purposes, twice the Na+
concentration equals serum osmolality because
urea and glucose ordinarily are responsible for less
than 5% of the osmotic pressure.
Hyponatremia
• Determine serum osmolality to determine if its
isotonic, hypertonic, or hypotonic
hyponatremia.
• Most often due to excess body water as
opposed to decreased body sodium.
Hyponatremia
a. Isotonic hyponatremia
occurs when plasma solids dilute the Na+. This occurs
with hyperproteinemia and hyperlipidemia.
b. Hypertonic hyponatremia
occurs with uncontrolled diabetes and with the use of
mannitol. Treat by correcting the fluid deficit initially
with isotonic saline, then give insulin to decrease glucose
and hypotonic saline to correct free water deficit.
c. True hypotonic hyponatremia
is characterized by hypovolemic, hypervolemic, and
isovolemic. Differentiation is done by assessing ECF
volume: blood pressure, skin turgor, edema, ascites etc
Hyponatremia
(Na+ <136 mEq/L [mmol/L])
• Hypertonic Hyponatremia.
High osmolality. Water shifts from
intracellular to extracellular in response to
high concentrations of such solutes as
glucose or mannitol.
• The shift in water lowers the serum sodium;
however, the total body sodium remains the
same.
Hypotonic Hyponatremia.
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Low osmolality. Further classified based on clinical assessment of
extracellular volume status
• Isovolemic.
No evidence of edema, normal BP. Caused by water intoxication (urinary
osmolality <80 mOsm), SIADH, hypothyroidism, hypoadrenalism, thiazide
diuretics, beer potomania
• Hypovolemic.
Evidence of decreased skin turgor and an increase in heart rate and decrease in
BP after going from lying to standing. Due to renal loss (urinary sodium >20
mEq/L) from diuretics, postobstructive diuresis, mineralocorticoid deficiency
(Addison disease, hypoaldosteronism) or extrarenal losses (urinary sodium
<10mEq/L) from sweating, vomiting, diarrhea, third spacing fluids (burns,
pancreatitis, peritonitis, bowel obstruction, muscle trauma)
• Hypervolemic.
Evidence of edema. urinary sodium <10 mEq/L). Seen with CHF, nephrosis,
renal failure, and liver disease
Symptoms: Usually with Na+ <125
mEq/L (mmol/L)
• severity of symptoms correlates with the
rate of decrease in Na+.
• ?Lethargy, confusion, coma
• ?Muscle twitches and irritability, seizures
• ?Nausea, vomiting
• Signs:
Hyporeflexia, mental status changes
Treatment: Based on determination
of volume status.
• Evaluate volume status by physical
examination HR and BP lying and standing
after 1 min, skin turgor, edema and by
determination of the plasma osmolality.
• Do not need to treat hyponatremia from
pseudo-hyponatremia (increased protein or
lipids) or hypertonic hyponatremia
(hyperglycemia),
Treatment: Based on determination
of volume status.
Life-Threatening. (Seizures, coma) 3-5% NS can be given in the ICU
setting. Attempt to raise the sodium to about 125 mEq/L with 3-5%
NS.
Isovolemic Hyponatremia. (SIADH)
• Restrict fluids (1000-1500 mL/d).
• Demeclocycline can be used in chronic SIADH.
Hypervolemic Hyponatremia
• Restrict sodium and fluids (1000-1500 mL/d).
• Treat underlying disorder. CHF may respond to a combination of ACE
inhibitor and furosemide.
Hypovolemic Hyponatremia
• Give D5NS or NS.
Hypernatremia
1. Less common than hyponatremia, usually
iatrogenic.
2. Occurs with either pure water loss, hypotonic fluid
loss, or salt gain.
3. Most commonly we see patients with both water
and sodium loss, but water loss exceeds salt loss.
4. Water loss from increased insensible loss, fever,
burn, diabetes insipidus
5. Diabetes Insipidus
Hypernatremia (Na+ >144 mEq/L
[mmol/L])
• Mechanisms: Most frequently, a deficit of
total body water.
• (Hypovolemic hypernatremia).
• (Isovolemic hypernatremia).
• (Hypervolemic hypernatremia).
Hypernatremia (Na+ >144 mEq/L
[mmol/L])
• Mechanisms: Most frequently, a deficit of total
body water.
• Combined Sodium and Water Losses
(Hypovolemic hypernatremia).
• Water loss in excess of sodium loss results in
low total body sodium.
• Due to renal (diuretics, osmotic diuresis due to
glycosuria, mannitol, etc) or extrarenal
(sweating, GI, respiratory) losses
Hypernatremia (Na+ >144 mEq/L
[mmol/L])
• Excess Water Loss (Isovolemic
hypernatremia).
• Total body sodium remains normal, but
total body water is decreased. Caused by
diabetes insipidus ,excess skin losses,
respiratory loss, others.
Hypernatremia (Na+ >144 mEq/L
[mmol/L])
• Excess Sodium (Hypervolemic
hypernatremia).
• Total body sodium increased, caused by
iatrogenic sodium administration (ie,
hypertonic dialysis, sodium-containing
medications) or adrenal hyperfunction
(Cushing’s syndrome, hyperaldosteronism).
Hypernatremia
• Symptoms:
Depend on how rapidly the sodium level has
changed
• Confusion, lethargy, stupor, coma
• Muscle tremors, seizures
• Signs:
Hyperreflexia, mental status changes
Hypernatremia:
Treatment:
• Hypovolemic Hypernatremia. Determine
if the patient volume is depleted by
determining if orthostatic hypotension is
present;
• if volume is depleted, rehydrate with NS
until hemodynamically stable,
• then administer hypotonic saline (1/2 NS).
Hypernatremia:
Treatment:
• Euvolemic/Isovolemic. (No orthostatic
hypotension) calculate the volume of free water
needed to correct the Na+ to normal as follows:
• Body water deficit = Normal TBW - Current TBW
Where Normal TBW = 0.6 x Body weight in kg
• And Current TBW =Normal serum sodium x
TBW / Measured serum sodium
• Give free water as D5W, one-half the volume
in the first 24 h and the full volume in 48 h.
(Caution: The rapid correction of the sodium
level using free water (D5W) can cause
cerebral edema and seizures.)
Hypervolemic Hypernatremia
• Avoid medications that contain excessive
sodium
(carbenicillin, etc).
Use furosemide along with D5W.
Treatment of hypernatremia
• Hypotonic fluid loss is the most common form of
hypernatremia.
• It is caused by gastroenteritis, osmotic diuresis.
• Signs of intravascular depletion are evident.
• Treatment involves replacement volume with
normal saline, followed by correction of the free
water deficit
Hypercalcemia
C a2+ > 10.2 mg/dL (2.55 mmol/L)
Mechanisms
• Parathyroid-Related. Hyperparathyroidism with secondary bone resorption
• Malignancy-Related. Solid tumors with metastases (breast, ovary, lung,
kidney), or paraneoplastic syndromes, (squamous cell, renal cell, transitional
cell carcinomas, lymphomas, and myeloma)
• Vitamin-D-Related. Vitamin D intoxication, sarcoidosis, other
granulomatous disease
• High Bone Turnover. Hyperthyroidism, Paget’s disease, immobilization,
vitamin A intoxication
• Renal Failure. Secondary hyperparathyroidism, aluminum intoxication
• Other. Thiazide diuretics, milk alkali syndrome, exogenous intake
Symptoms
• Stones (renal colic) bones (osteitis fibrosa), moans
(constipation), and groans (neuropsychiatric
Symptoms e.g confusion), as well as polyuria,
polydipsia, fatigue, anorexia, nausea, vomiting
Signs
• Hypertension, hyporeflexia, mental status changes
• Shortening of the QT interval on the ECG.
Treatment:
• Usually emergency treatment if patient is
symptomatic and Ca+2 >13 mEq/L (3.24 mmol/L)
• Use saline diuresis: D5NS at 250-500 mL/h.
• Give furosemide (Lasix) 20-80 mg or more IV
(saline and Lasix will treat most cases).
• Euvolemia or hypervolemia must be maintained.
Hypovolemia results in calcium reabsorption.
Other Second-Line Therapies:
• Calcitonin 2-8 IU/kg IV or SQ q6-12h if diuresis
has not worked after 2-3h
• Pamidronate 60 mg IV over 24 h (one dose only)
• Gallium nitrate 200 mg/m2 IV infusion over 24 h
for 5 d
• Plicamycin 25 micg/kg IV over 2-3 h (use as last
resort; very potent)
• Corticosteroids. Hydrocortisone 50-75 mg IV
every 6 h.
• Consider hemodialysis.
Hypocalcemia
C a2+ < 8.4 mg/dL (2.1 mmol/L)
Mechanisms: Decreased albumin can result in decreased calcium
• PTH. Responsible for the immediate regulation of calcium levels
• Critical Illness. Sepsis and other ICU-related conditions can cause decreased
calcium because of the fall in albumin often seen in critically ill patients,
ionized calcium may be normal.
• PTH Deficiency. Acquired (surgical excision or injury, infiltrative diseases
such as amyloidosis or hemachromatosis and irradiation) hereditary
hypoparathyroidism (pseudo-hypoparathyroidism), hypomagnesemia
• Vitamin D deficiency. Chronic renal failure, liver disease, use of phenytoin or
phenobarbital, malnutrition, malabsorption (chronic pancreatitis,
postgastrectomy)
• Other. Hyperphosphatemia, acute pancreatitis, osteoblastic metastases,
medullary carcinoma of the thyroid, massive transfusion
Symptoms
• Hypertension, peripheral and perioral paresthesia,
abdominal pain and cramps, lethargy, irritability (in
infants)
Signs
• Hyperactive DTRs, carpopedal spasm (Trousseau’s sign)
• Positive Chvostek’s sign (facial nerve twitch, can be
present in up to 25% of normal adults).
• Generalized seizures, tetany, laryngospasm
• Prolonged QT interval on ECG
Treatment
Acute Symptomatic
• 100-200 mg of elemental calcium IV over 10 min
in 50-100 mL of D5W followed by an infusion
containing 1-2 mg/kg/h over 6-12 h
• 10% calcium gluconate contains 93 mg of
elemental calcium.
• 10% calcium chloride contains 272 mg of
elemental calcium.
• Check magnesium levels and replace if low.
Chronic
• For renal insufficiency, use vitamin D along
with oral calcium supplements
Hypermagnesemia
Mg2+ > 2.1 mEq/L (mmol/L)
Mechanisms
• Excess Administration. Treatment of
preeclampsia with magnesium sulfate
• Renal Insufficiency. Exacerbated by
ingestion of magnesium-containing antacids
• Others. Rhabdomyolysis, adrenal
insufficiency
Hypermagnesemia
Mg2+ > 2.1 mEq/L (mmol/L)
• Symptoms and Signs
• 3-5 mEq/L(mmol/L): Nausea, vomiting,
hypotension
• 7-10 mEq/L (mmol/L): Hyperreflexia,
weakness, drowsiness
• >12 mEq/L (mmol/L): Coma, bradycardia,
respiratory failure
Hypermagnesemia
Mg2+ > 2.1 mEq/L (mmol/L)
Treatment:
Clinical hypermagnesemia requiring therapy is infrequently encountered
in the patient with normal renal function.
• Calcium gluconate: 10 mL of 10% solution (93 mg elemental calcium)
over 10-20 min in 50-100 mL of D5W given IV to reverse symptoms
(useful in patients being treated for eclampsia).
• Stop magnesium-containing medications (hypermagnesemia is most
often encountered in patients in renal failure on magnesium-containing
antacids).
• Insulin and glucose as for hyperkalemia ,Furosemide and saline
diuresis
• Dialysis
Hypomagnesemia
Mg2+ <1.5 mEq/L (mmol/L)
Mechanisms
• Decreased Intake or Absorption. Malabsorption, chronic
GI losses, deficient intake (alcoholics), TPN without
adequate supplementation
• Increased Loss. Diuretics, other medications (gentamicin,
cisplatin, amphotericin B, others), RTA, diabetes mellitus
,alcoholism, hyperaldosteronism,
• excessive lactation
• Other. Acute pancreatitis, hypoalbuminemia, vitamin D
therapy.
Hypomagnesemia
Mg2+ <1.5 mEq/L (mmol/L)
Symptoms
• Weakness, muscle twitches, Vertigo
• Symptoms of hypocalcemia (hypomagnesemia
may cause hypocalcemia and hypokalemia)
Signs
• Tachycardia, tremor, hyperactive reflexes, tetany,
seizures
• ECG may show prolongation of the PR, QT, and
QRS intervals as well as ventricular ectopy, sinus
tachycardia
Hypomagnesemia
Mg2+ <1.5 mEq/L (mmol/L)
Treatment
Severe: Tetany or Seizures Monitor patient with ECG in ICU setting.
• 2 g magnesium sulfate in D5W infused over 10-20 min. Follow with
magnesium sulfate:1 g/h for 3-4 h follow DTR and levels. Repeat
replacement if necessary.
• These patients are often hypokalemic and hypophosphatemic as well
and should be supplemented.
• Hypocalcemia may also result from hypomagnesemia.
Moderate
• Mg2+ <1.0 mg/dL but asymptomatic
• Magnesium sulfate: 1 g/h for 3? h, follow TR and levels and repeat
replacement if necessary.